On October 30, 1999, at 1420 hours Pacific daylight time, a Cessna 305A, N5198G, owned and operated by the pilot, veered off the runway and nosed over during landing rollout at the Zamperini Field, Torrance, California. Visual meteorological conditions prevailed at the time of the personal flight, and no flight plan was filed. The airplane was substantially damaged. Neither the commercial certificated pilot nor the passenger was injured. The flight was conducted under the provisions of 14 CFR Part 91, and it originated from Carlsbad, California about 1315. The pilot reported to the Safety Board investigator that as he approached the airport he heard the automatic terminal information service broadcast (ATIS). He stated, however, that he did not realize he would experience a quartering tailwind during landing. The wind was reported at 300 degrees, 10 knots. The pilot further reported that he performed a normal three-point touchdown in his conventional gear airplane. An air traffic controller, who witnessed the accident, reported that the airplane landed on the runway and no evidence of bouncing was observed. The pilot stated that after rolling for several hundred feet he applied right rudder to correct for a (left quartering) tailwind. However, the tail wheel steering did not function properly. Thereafter, he lost control, veered off the runway into the adjacent plowed field, and nosed over. The pilot stated that a malfunction in the airplane's tail wheel control system contributed to his inability to steer the airplane. The tail wheel assembly was subsequently examined. An internal tail wheel centering spring was found broken. The total time on the part was about 400 hours.